Week 1.02 Anatomy And Physiology

Question 1

What shape is the cornea

Answer 1

Aspheric

Prolate eclipse with p value between 0 and 1

Question 2

One position keratometer

Answer 2

Mire reflected on cornea
Once mire found alter separation of mires until end point found
Twist knob to get pluses overlap and another knob to get minus to overlap
Look at measurements the machine shows

Question 3

Two positive keratometer

Answer 3

Only measures one meridian at a time
Needs to be rotated for second measurement
Adjust mires till they meet

Question 4

What’s the difference between one position and two position keratometer

Answer 4

One position keratometer has fixed mires but variable doubling
Two position keratometer has variable mires but fixed doubling

Question 5

0.05mm difference is how much difference in power

Answer 5

0.25D

Question 6

What is the average corneal dimensions

Answer 6

Radius - 7.86mm
Diameter - 11.8mm
Centre thickness - 0.52mm
Peripheral thickness - 1mm

Question 7

How can you tell the difference between microcysts and vacuoles

Answer 7

Microcysts show reverse illumination - bright side on OPPOSITE side to light

Vacuole show unreversed illumination - bright side of vacuole on SAME side as the bright side

Question 8

What does it mean if px has stromal striae

Answer 8

Px needs more o2

Question 9

What’s the management to vascularisation

Answer 9

Cease lens wear
Or if mild increase o2 permeability, reduce wearing time and/or refit with RGP

Question 10

Endothelial disorders

Answer 10

Polymegathism - cells that appear to vary in size more than is normal

Polymorphism - shape of cells changes and becomes much more variable

Endothelial blebs - looks like gaps in the endothelial mosaic

Question 11

What is contact lens induced papillary conjunctivitis (CLIPC)

Answer 11

Response triggered by cls wear
Deposits on lens
Looks like papillae on superior palpebral conjunctiva so lid eversion important